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   "cell_type": "markdown",
   "id": "6aa0b114-1f8d-4098-9b75-3eae02222f69",
   "metadata": {},
   "source": [
    "第三周作业"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 5,
   "id": "a6f49797-425c-4b98-a3be-7036740174e5",
   "metadata": {},
   "outputs": [
    {
     "name": "stdin",
     "output_type": "stream",
     "text": [
      "请输入一个正整数： 4\n"
     ]
    },
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "24\n"
     ]
    }
   ],
   "source": [
    "k = int(input('请输入一个正整数：'))\n",
    "m = 1\n",
    "for i in range(1,k+1):\n",
    "    m = m*i\n",
    "print(m)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 8,
   "id": "b86bb3f5-ff5d-4677-8b82-e7ec3582931b",
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "False\n"
     ]
    }
   ],
   "source": [
    "def is_prime(n):\n",
    "    if n <= 1:\n",
    "        return False\n",
    "    if n == 2:\n",
    "        return True\n",
    "    if n % 2 == 0:\n",
    "        return False\n",
    "    for i in range(3, int(n**0.5) + 1, 2):\n",
    "        if n % i == 0:\n",
    "            return False\n",
    "    \n",
    "    return True\n",
    "\n",
    "print(is_prime(189))"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 12,
   "id": "6537fb15-265d-4e08-8b31-cc71be3f2168",
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "iahgnahs\n"
     ]
    }
   ],
   "source": [
    "def reverse_string(s):\n",
    "    return s[::-1]\n",
    "\n",
    "print(reverse_string(\"shanghai\"))"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 13,
   "id": "d8034ed3-8305-48aa-9c98-40608ba03a52",
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "[0, 1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89, 144, 233, 377, 610, 987, 1597, 2584, 4181, 6765, 10946, 17711, 28657, 46368, 75025, 121393, 196418, 317811, 514229, 832040, 1346269, 2178309, 3524578, 5702887, 9227465, 14930352, 24157817, 39088169, 63245986, 102334155, 165580141, 267914296, 433494437, 701408733, 1134903170, 1836311903, 2971215073, 4807526976, 7778742049, 12586269025, 20365011074, 32951280099, 53316291173, 86267571272, 139583862445, 225851433717, 365435296162, 591286729879, 956722026041, 1548008755920, 2504730781961, 4052739537881, 6557470319842, 10610209857723, 17167680177565, 27777890035288, 44945570212853, 72723460248141, 117669030460994, 190392490709135, 308061521170129, 498454011879264, 806515533049393, 1304969544928657, 2111485077978050, 3416454622906707, 5527939700884757, 8944394323791464, 14472334024676221, 23416728348467685, 37889062373143906, 61305790721611591, 99194853094755497, 160500643816367088, 259695496911122585, 420196140727489673, 679891637638612258, 1100087778366101931, 1779979416004714189]\n"
     ]
    }
   ],
   "source": [
    "def fibonacci(n):\n",
    "    if n <= 0:\n",
    "        return []\n",
    "    elif n == 1:\n",
    "        return [0]\n",
    "    elif n == 2:\n",
    "        return [0, 1]\n",
    "    \n",
    "    fib_sequence = [0, 1]\n",
    "    for i in range(2, n):\n",
    "        next_fib = fib_sequence[i-1] + fib_sequence[i-2]\n",
    "        fib_sequence.append(next_fib)\n",
    "    \n",
    "    return fib_sequence\n",
    "\n",
    "print(fibonacci(90))"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "id": "3976b5c3-51d6-439e-bf22-509f8cd81ecb",
   "metadata": {},
   "outputs": [],
   "source": [
    "def find_max(numbers):\n",
    "    if not numbers:  \n",
    "        return None\n",
    "    \n",
    "    max_value = numbers[0]  \n",
    "    \n",
    "    for num in numbers[1:]: \n",
    "        if num > max_value:\n",
    "            max_value = num\n",
    "    \n",
    "    return max_value"
   ]
  }
 ],
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